The white, sticky substance often noticed in the eye upon waking is medically known as rheum. This material is a normal byproduct of the eye’s natural cleaning process, representing a collection of elements the eye produces and sheds to maintain a healthy surface. While the presence of this discharge is generally not a cause for concern, changes in its consistency, color, or amount can signal an underlying eye condition. Understanding the characteristics of this discharge is the first step toward determining if it is simply “sleep” or a sign of an issue requiring attention.
The Anatomy of Eye Discharge
The substance that collects in the corner of your eye is a complex mixture derived from your tear film and the cells of the eye’s surface. A primary component is mucin, a thin mucus produced by cells in the conjunctiva, which traps foreign particles and cellular debris throughout the day.
The discharge also contains meibum, an oily secretion from the meibomian glands located along the eyelid margins. This oil helps prevent tear evaporation, and when mixed with the mucin and debris, it contributes to the sticky texture. While blinking washes this mixture away through the tear ducts during the day, the material collects and dries when you sleep.
Differentiating Normal Sleep Crust from Abnormal Discharge
Normal rheum, often called “sleep,” is typically a small amount of dry, crusty material found only in the corners of the eyes upon waking. It is usually white, clear, or a pale cream color and can be easily wiped away. This material collects overnight because the lack of blinking prevents it from being flushed out.
Abnormal discharge presents with differences in appearance, consistency, and timing. If the discharge is wet, sticky, and continuous throughout the day, it suggests a problem. A change in color to thick yellow, green, or gray indicates inflammatory cells and pus, signaling infection. This dense discharge may also glue the eyelids shut, requiring a warm compress to open the eyes.
Primary Causes of Excessive Eye Goop
The appearance of excessive or colored discharge is often linked to infectious, allergic, or inflammatory conditions. The most frequent cause is conjunctivitis (pink eye), which involves inflammation of the conjunctiva. Identifying the specific type of discharge helps narrow down the cause.
Infectious Causes
Infectious conjunctivitis can be viral or bacterial, producing different types of discharge. Viral pink eye usually results in a clear, watery discharge that may contain thin, white mucus. Bacterial conjunctivitis, conversely, is characterized by a thick, purulent discharge that is yellow, green, or gray. This material is highly contagious and often causes the eyelids to be glued shut in the morning.
Allergic Causes
Allergic reactions to irritants like pollen or pet dander also trigger excessive eye discharge, which is not contagious. Allergic conjunctivitis often causes intense itching and watery eyes. The discharge is typically a stringy, thick white or clear mucus. This stringy consistency differentiates it from the thin, watery discharge of a viral infection and the thick, pus-like discharge of a bacterial one.
Chronic Irritation
Other common causes of white or clear discharge relate to chronic irritation and inflammation of the eyelid margins. Dry eye syndrome, where the eyes do not produce enough quality tears, can cause the body to overcompensate, resulting in excessive mucus production that appears as stringy or clear discharge. Similarly, blepharitis, an inflammation of the eyelids often involving the oil glands, can produce a foamy or crusty white/clear discharge along the base of the eyelashes.
Warning Signs and When to Consult a Doctor
While small amounts of white, crusty morning residue are typical, certain accompanying symptoms are red flags that warrant prompt medical consultation. Any discharge that is thick and changes color to dark yellow, green, or gray is a sign of a likely bacterial infection and requires a professional assessment.
Immediate attention is necessary if the discharge is accompanied by:
- Severe eye pain.
- A sudden change in vision.
- Increased sensitivity to light (photophobia).
- Swelling or redness that worsens.
- A foreign body sensation that does not resolve.
- Crusting that consistently prevents the eyes from opening.
Initial management involves basic hygiene, such as avoiding touching the eyes and using a clean, warm compress to gently loosen dried discharge.